Liquid immersed rheostat



March 29, 1949. G1BSON LIQUID IMMERSED RHEOSTAT 4 Sheets-Sheet 1 Filed July 16, 1946 I (DH/o,

I iij( March 29, 1949. T. GIBSON 2,465,524

LIQUID IMMERSED RHEOSTAT Filed July 16', 1946 1 4 Sheets-Sheet 2 INSULATION March 29, 1949. v T. M. GIBSON 2,465,524

LIQUID IMMERSED RHEOSTAT Filed July 16, 1946 A 4 Sheets-Sheet 5 Q Q 6 0mm w QQQQ Q March 29, 1949-. T. M. GIBSON 2,465,524

LIQUID IMMERSED RHEOSTAT Filed July is, 1946 4 Sheets-Sheet 4 V IIIIV 52 31 INSULATION 15 INSULATION Patented Mar. 29, 1949 LIQUID IMMERSED RHEOSTAT Thomas M. Gibson, West Haven, Conn, assignor to Exacta Manufacturing 00., Inc., New Haven, Conn, a corporation of Connecticut Application July 16, 1946, Serial No. 684,059

9 Claims.

This invention relates to a rheostat unit, and particularly a rheostat unit for use in the electroplating industry, where the parts of the device would normally be exposed to the atmosphere existing in a plating room.

In the usual process employed in the electrodeposition of metals, such, for example, as nickel, chromium, cadmium, zinc, copper, gold, silver, or almost any other metal commercially depositable by the passage of an electric current through a solution of its salts, the air in the plating room in which the process is carried on becomes more or less contaminated by the plating bath. Where the resistors and other parts of the rheostat and its accompanying equipment, such as switches, for example, are exposed to this air, corrosion of these parts occurs, as these elements are subject to the formation of metallic salts by the action of acids or other compounds employed in the plating operation. This corrosion sometimes causes the resistor elements, for example, to become eroded or eaten away, and where the resistor switches are attacked, corrosion always results in very high resistance in the contacts, which either interrupts or greatly reduces the current passing therethrough.

Also in many plating operations a current of high amperage is employed, this requiring resistors of considerable capacity. The passage of the current through the resistors of the rheostat gives rise to a certain amount of heat, which, in turn, increases the resistance of the resistor elements and thus cuts down the capacity of the rheostat. I also contemplate by the present invention maintaining the resistor eements at a low temperature, as well as the protection of the resistor elements and associated electrical equipment, such as switches, from the deleterious effects of corrosion caused by the exposure of these elements to the contaminated air of the plating room.

To efiect these advantageous results, I enclose the resistors, as well as other associated parts of the rheostat, such as the switches, in a closed case or container, which may be filled to a proper level with .some fluid such as oil, for example, the requirements for the fluid being that it be a nonconductor of electricity, that it be a conductor of heat, and that it will not attack the metal of the parts which are submerged therein. The case or container in which the parts of the rheostat are contained is filled with this fluid, to such a depth that all of the parts which it is necessary to protect from the atmosphere of the plating room will be submerged therein.

The controls for the switches are mounted upon the outsideof the case, and are brought through the case at a point above the level of the oil therein, so that there will be no danger of leakage, and this is also true of wires and conductors or other elements which necessarily pass through the walls of the case.

One object of my invention is to provide a new and improved rheostat unit for use in connection with electroplatin and the like.

A further object of my invention is to provide a rheostat unit for use in the electroplating industry, so constructed that the resistors of the rheostat and associated electrical equipment, such as switches, will be protected against corrosion which commonly occurs from exposure to the contaminated air of a plating room.

A still further object of the invention is to provide a rheostat unit for use in the electroplating industry, wherein the elements of the rheostat will be protected from corrosion and will also be kept from becoming heated, this being effec ed by the immersion of these elements in a fluid such as oil, which will both prevent corrosion and thus preserve the parts of the rheostat, and also conduct the heat from the resistors, for example, to the case, where it will be dissipated to the air, and, in addition, sparking at the switch contact points will also be prevented.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

, Fig. 1 is a top plan view of a rheostat unit embodying my invention, the unit being enclosed in a-case or container; I

Fig. 2 is a front elevatlonal view thereof;

Fig. 3 is a top plan view of the unit, the cover bein removed to show the interior mechanism; Fig. 4 is a sectional view on line 4-4 of Fig. 2; Fig. 5 is a detail end elevational view of the resistor units; Fig. 6 is a sectional view taken substantially on line 6-6 of Fig. 5, but also showing the position of the interior mechanism relatively to the adjacent wall of the case;

Fig. '7 is a detail view of the method of securing the resistor units to the end supporting plates;

Fig. 8 is a sectional view on line 8-8 of Fig. '7; Fig. 9 is a sectional view of one of the switchcontrol knobs;

Fig. 10 is a view of the rear face of one of the switch-control knobs; Fig. 11 is a diagrammatic view showing the be properly protected from exposure to the atmosphere of the plating room, as will be hereinafter described.

Within the case are mounted two resistor units, designated generally by the numerals l3 and I4. As shown in the diagrammatic view of Fig. 11, these resistor units are placed in parallel in the circuit passing through the plating bath and the original source of current, and as their construction is substantially identical, a description of one will suflice for both. Each of these units comprises a pair of end plates l5 and IS, the former being of insulating material and the latter of conducting material, these plates being secured together by spacer bars l5 (Figs. 3 and 4). These end plates are carried by arms or hangers il secured to the plates at l8, and secured by bolts i9 to lugs 20 on the body of the case.

- To each of the end plates 15 and I6 are secured a plurality of studs 22, these studs being threaded as at 23, and also being split or slotted through their outer ends, as shown at 24. They are also provided with openings 25, within which may be received terminal members 26 of cylindrical shape, to which terminal members are secured the ends of the resistance elements 21. The members 26 are slightly larger in diameter than thenormal diameter of the openings 25, so that when these elements are placed in the openings, the parts of the stud 22 are spread to some extent, and may thereafter be brought together to clamp the elements 26 by means of the locking nut 28 mounted upon the threads 23. Thus the resistance elements 21 may be readily and replaceably locked in position so that they will be firmly held in place, and at the same time easily removed, if necessary, while a good contact is also assured.

' As shown in Fig. 3, the two resistor units are placed side by side, but are reversed one relatively t the other in that the conducting plate l6 of one is adjacent the insulated supporting plate l of the other.

The studs 22 upon the insulating plates are provided with flattened heads 30 upon the 0utside of these plates, to provide contact elements adapted to be engaged by a switch contact plate 3| of segmental shape, which plate is mounted upon a shaft 32 rotatably carried by the plate l5, the member 3| having a hub 33 secured by the set screw 34 to the shaft 32. 1

It will be seen, therefore, that the resistance elements 21 extend from one of the plates l5 to the associated plate l6 at the opposite end of the casing, and that, as the plate [6 is of conducting material, these resistors are all electrically connected at that end of the plate through the studs 22, which are also of conductive material. At the other end, however, that is, at the plate |5 which is of insulating material, the studs 22 will be insulated from each other. The switch contact element 3| may be slotted, as shown at 36, to provide resilient tongues 31 properly spaced to engage the members 30, and the latter may thus be electrically connected to a fixed contact 38 mounted on each of the plates l5, as the element 3| will always engage this contact. It will be seen, therefore, that as many of the resistors desired may be placed into electrical contact with the member 38, and therefore placed in the circuit through the plating bath.

The shaft 32 is provided with a bevel gear to the teeth of which mesh with a bevel gear 45 secured to a shaft 46, which is rotatably carried by a bracket 41, this bracket being secured by bolts 41 to the plate l5 (Fig. 6) and also being carried by one of the spacer bars I5 (Fig. 4). The upper end of the shaft 46 has secured thereto a bevel gear 48 which meshes with a bevel gear 49 mounted on a horizontal shaft 50 (Figs. 3 and 4) rotatably mounted in the bracket 4'! and in the wall of the casing.

The shaft 50 extends without the casing, and on its extended end is secured a knob 5| by which the shaft may be rotated so as to rotate the contact segment 3| and thus vary the number of resistance elements 21 which are placed in the circuit through the bath. The inner face of the knob 5| is provided with an arcuate recess 52 (Figs. 9 and 10) having therein a number of depressions 53 to receive a spring-pressed ball 54 mounted in a sleeve 55 secured in the casing wall. This provides readily releasable means for holding the knob 5| at definite stations in its turning movement, according to the spacing of the depressions 53, to cause the resilient tongues 31 of the contact member 3| to properly register with the contact members 30.

As previously stated, the parts just described are duplicated for each set of resistor elements, except that, as one of the insulating plates I5 is at the back of the casing and the other at the front, the shaft 50, which corresponds to the shaft 50, must be longer than the shaft 50 in order to extend to the rear of the casing. The knobs 5| are both at the front of the case, and, as will be seen from Fig. 4, the shafts 50 and 50, which extend through the case, are above the level of the oil 57 contained within the case, the level of this oil, however, being sufiiciently high to cover the plates l5 and I6, and therefore cover the resistance elements 21 and the switch elements 30, 3| and 38. Thus all of the interior mechanism within the case will not only be protected from exposure to the atmosphere, but the heat developed in these elements will be transmitted to the case by the oil within which they are immersed. In order that this heat be dissipated to the air, both the body and the top of the case are provided with cooling fins 58.

60 and 6| designate ammeter and voltmeter dials mounted upon the front of the case between the knobs 5|, so that the amperage and voltage of the current passing through the plating bath may be read, and the knobs themselves may have indicia 62 and 63 thereon to show which of the resistance elements have been placed in the circuit. As the two resistor units are in parallel, one of the knobs will read from 1 to 8, and the other from 9 to 16, there being 8 of the resistance elements 21 in each of the units.

If desired, a bi-metallic thermostatic element 64 (Figs. 2 and 12) may be immersed within the oil so as to give an alarm if the temperature developed within the case becomes excessive. This bi-metallic element is adapted to close a circuit through a cooperating fixed contact 65, the memamuse bers 64 and 68 having connected thereto currentca'rryingwires 66 and 61, which, as shown inlets. 1. lead to a signal lamp 68 mounted at the front 01 the casing, so that the lamp will-be illuminated when the temperature becomes too high. The main current leads or bus bars are shown at 68 and 10, and lead through the cover ll of the casing, the openings through which they pass being, of course, above the level of the oil :51;

The illustrative wiring diagram is shown in Fig. 11, although it will be understood that the particular manner of making the electrical connections may be varied, as desired. The main source of current is shown at H, one of the terminals of which leads to the bus bar 69 and the other to the plating bath 12, from which a conductor 13 leads to the other bus bar 10. The latter bus bar may be connected directly to one of the plates [6, which plate is connected by a con ductor 14 to the plate l6 of the other unit. The bus bar 69 is connected by means of conductors 15 and 16 to the contact members 38 on the insulating plates l5. Thus, it will be seen that, as the plates l6 are of conducting material, any of the resistance elements 21 will be placed in the circuit when their contacts 30 are connected to the contacts 38 by means of the rotatable switch plate 3|,

The ammeter 60 may be connected in'shunt across a part of the bus bar 69, as shown at 18, while the voltmeter 6! may be connected across the bus bars 69 and 10.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

l. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a removable closure member for the casing, a resistor unit within the casing below the closure member, said casing containing oil within which the resistor unit is immersed, a switch mechanism in the casing to place the resistor in the plating circuit, said mechanism being disposed below the level of the oil in the casing, a switch-operating member mounted exteriorly on the casing, and a connection between said member and said mechanism, said connection passingthrough the casing at a point above the level of the oil therein.

2. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a removable closure member for the casing,

a. resistor unit within the casing below the closure member, said casing containing oil within which the resistor unit is immersed, aswitch mechanism in the casing to place the resistor in the plating circuit, said mechanism being disposed below the level of the oil in the casing, said mechanism comprising a rotatable control member, and means mounted exteriorly of the casing and above the level of the oil therein for actuating said member.

3. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a removable closure member for the casing, a resistor unit within the casing below the closure member, said casing containing oil within which the resistor unit is immersed, a switch mechanism in the casing to place the resistor in the plating circuit, said mechanism being disposed below the level of the oil in the casing, said mechanism comprising a rotatable control member, means mounted exteriorly of the casing and above 6 level- ''of the oil' therein for actuating said member, and a gear train'connection between said means and said member.

4. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a resistor unit within the casing, said casing containing oil to a level above the top of said unit, said unit comprising a pair of end plates, one adjacent each end of the casing, and resistance elements extending between and secured to said plates.

5. A rheostat structure for use in an electroplating circuit, said structure comprising 2. casing, a resistor unit within the casing, said casing containing oil to a level above the top of said unit, said unit comprising a pair of end plates, one adjacent each end of the casing, resistance elements extending between and secured to said plates, one of said plates being of insulating material and having a plurality of contacts thereon, certain of which are each connected with one of said elements, and a cooperating contact plate rotatably mounted on said insulating plate and adapted to be placed in engagement with said contacts.

6. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a resistor unit Within the casing, said casing containing oil to a level above the top of said unit,

said unit comprising a pair of end plates, one adjacent each end of the casing, resistance elements extending between and secured to said plates, one of said plates being of insulating material and having a plurality of contacts thereon, certain of which are each connected with one of said elements, a cooperating contact plate rotatably mounted on said insulating plate and adapted to be placed in engagement with said contacts, and means mounted exteriorly of the casing for rotating said contact plate.

7. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a resistor unit within the casing, said casing containing oil to a level above the top of said unit,

. said unit comprising a pair of end plates, one adjacent each end of the casing, resistance elements extending between and secured to said plates, one of said plates being of insulating material and having a plurality of contacts thereon, certain of which are each connected with one of said elements, a co-operating contact plate rotatably mounted on said insulating plate and adapted to be placed in engagement with said contacts, the other of said end plates being of conducting material, and circuit leads entering the casing above the level of the oil therein and respectively connected to said last-named end plate and to a con tact on the insulating plate.

8. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a resistor unit within the casing, said casing containing oil to a level above the top of said unit, said unit comprising a pair of end plates, resistance elements extending between said plates, and studs secured to said end plates and having transverse openings therethrough and being slotted from their ends through said openings, said elements having terminal members thereon clamped in said openings.

9. A rheostat structure for use in an electroplating circuit, said structure comprising a casing, a resistor unit within the casing, said casing containing oil to a level above the top of said unit, said unit comprising a pair of end plates, resistance elements extending between said plates,

studs secured t6 said end plates having transverse openings therethrough, and cylindrical terminal 8 UNITED STATES PATENTS Date' Name Waters Oct. 30, 1906 Bliss July 22, 1919 Planche July 17, 1934 FOREIGN PATENTS I Country Date Italy Sept. 21, 1929 

